JPH11304069A - Electrically fusing joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fusion-connect a resin pipe with a sufficient strength even if an oxide film is present of the fusing connecting surface of the resin pipe by forming a recessed groove allowing the inflow of a fused resin in fusing connection on the inside surface of a cylindrical fusing part in an electrically fusing joint having a heating wire buried in the inside part of the cylindrical fusing part for fusion connecting the resin pipe. SOLUTION: An electric fusing joint 10 comprises a heating wire 12 buried in the inside part of a cylindrical fusing part 11 for fusion connecting a resin pipe, and a terminal pin 13 connected to one end of the heating wire 12 and an indicator 14 for displaying the fusing completion are provided on the circumference. One or a plurality of recessed grooves 15 is provided on the inside surface of the fusing part 11 having the heating wire 12 buried therein. When then end part of a resin pipe 16 is inserted and fusion connected, a fused resin 17 including an oxide film is made to flow into the recessed groove 15. According to this, the fused resin on the inside surface of the fusing part 11 can be sufficiently mixed with the fused resin on the outside surface of the resin pipe 16 in the state free from the oxide film, so that the fusion connection can be performed with a sufficient strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric fusion joint and, more particularly, to heat a heating wire embedded in an inner peripheral portion of a cylindrical fusion portion to fuse a contact surface between the fusion portion and a resin pipe. The present invention relates to an electric fusion joint for joining resin pipes by joining the resin tubes.

[0002]

2. Description of the Related Art Conventionally, as a means for connecting resin pipes used for various pipes, an electric fusion joint 1 as shown in a sectional view in FIG. 5 has been widely used. This electric fusion joint 1
The heating wire 3 is buried in the inner peripheral portion of the cylindrical fusion part 2 into which the resin pipe to be connected is inserted. When the resin pipe is connected, the electric fusion joint 1 is fused. After the end of the resin tube is inserted into the portion 2, the heating wire 3 is energized to generate heat, and the contact surfaces between the fusion portion 2 and the resin tube are melted.
It is formed so that the electric fusion joint 1 and the resin tube are fusion-bonded.

[0003]

However, if an oxide film is present on the fusion-bonded surfaces of the two, the mixing of the two molten resins becomes insufficient due to the oxide film, and the necessary bonding strength may not be obtained. Was. For this reason, when connecting the resin pipe using the electric fusion joint, it is necessary to remove the oxide film present on the fusion-bonded surface of the resin pipe. It took time.

[0004] That is, the insertion dimension of the end of the resin pipe into the electro-fusion joint is measured, and a wavy line or the like is drawn on the surface of that portion as a guide for surface cutting. I had to cut. At this time, even if the cutting amount is too large or insufficient, the fusion bonding with the joint may be incomplete. Further, if the cut surface is touched with the hand, it may not be possible to sufficiently perform the fusion bonding at that portion, so that consideration must be given to the handling of the resin tube after the cut.

Accordingly, an object of the present invention is to provide an electric fusion joint that can be fusion-bonded with sufficient strength even if an oxide film is present on the fusion-bonding surface of the resin tube.

[0006]

In order to achieve the above object, an electric fusion joint according to the present invention comprises an electric fusion joint in which a heating wire is embedded in an inner peripheral portion of a cylindrical fusion joint for fusion joining resin tubes. In the joint, a concave groove into which a molten resin at the time of fusion bonding can flow is formed on an inner peripheral surface of the cylindrical fusion bonding portion.

[0007]

1 to 4 show an embodiment of an electrofusion joint according to the present invention. FIG. 1 is a cross-sectional view of a main portion showing an embodiment of an electrofusion joint. FIG. FIG. 3 is a cross-sectional view showing one example of the shape of the groove, and FIG. 4 is a cross-sectional view showing another example of the shape of the groove.

An electric fusion joint 10 shown in FIG. 1 has a heating wire 12 buried in an inner peripheral portion of a cylindrical fusion portion 11 for fusion joining resin tubes, similarly to a conventional electric fusion joint. A terminal pin 13 connected to one end of the heating wire 12 and an indicator 14 for indicating completion of the fusion are provided on the outer periphery.
Are provided.

Then, the fused portion 11 in which the heating wire 12 is embedded
Is provided with one or more concave grooves 15 on its inner peripheral surface. As shown in FIG. 2, the concave groove 15 is
In order to allow the molten resin 17 containing an oxide film to flow in when performing the fusion bonding by inserting the end portions, the heating wire 12 generates heat by energization, and the inner peripheral surface of the fusion portion 11 When the resin and the resin on the outer peripheral surface of the resin tube 16 melt and expand,
It is provided in such a position and shape that the molten resin 17 including the oxide film flows.

As described above, the groove 1 is formed on the inner peripheral surface of the fused portion 11.
By providing 5, molten resin 17 containing an oxide film can flow into concave groove 15, so that the molten resin on the inner peripheral surface of fused portion 11 and the molten resin on the outer peripheral surface of resin tube 16 are oxidized. Sufficient mixing can be achieved without a film. Therefore, even if an oxide film is present on the outer peripheral surface of the joint portion of the resin tube 16, the two can be fused and joined with sufficient strength. Can be securely joined.

The shape of the groove 15 is arbitrary. As shown in FIG. 3, the groove 15 may be formed in a spiral shape on the inner peripheral surface of the fused portion 11, and the groove 15 on the right side in FIG. Fusion part 11
As shown in FIG.
5 may be provided, and a concave groove 15 may be provided on the inner peripheral surface of the fused portion 11 in an arc shape as shown in the fused portion 11 on the left side.
In addition, the shape, the arrangement position, and the like of the concave groove 15 can be appropriately set according to the diameter of the fused portion 11, the insertion dimension of the resin tube 16, and the like. Further, the present invention can be applied to electrofusion joints having various structures.

[0012]

As described above, according to the electric fusion joint of the present invention, the resin pipe can be fusion-bonded with sufficient bonding strength even if an oxide film exists on the fusion-bonding surface. This eliminates the need for an oxide film removing operation as in the prior art, and can greatly improve the workability in joining the resin tubes.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part showing one embodiment of an electrofusion joint of the present invention.

FIG. 2 is a cross-sectional view of a main part showing a state after resin pipe bonding.

FIG. 3 is a sectional view showing an example of a shape of a concave groove.

FIG. 4 is a cross-sectional view showing another example of the shape of the concave groove.

FIG. 5 is a cross-sectional view showing an example of a conventional electric fusion joint.

[Explanation of symbols]

10 ... electric fusion joint, 11 ... fusion part, 12 ... heating wire, 1
5 ... groove, 16 ... resin tube, 17 ... molten resin containing oxide film

Claims (1)

[Claims] 1. An electric fusion joint in which a heat generating wire is buried in an inner peripheral portion of a cylindrical fusion portion for fusion-bonding a resin tube to an inner peripheral surface of the cylindrical fusion portion. An electric fusion joint characterized by forming a concave groove into which a molten resin can flow.